LExEn: Integrated Biogeochemical and Microbiological Studies of Cold, Anoxic Environments

LExEn：寒冷缺氧环境的生物地球化学和微生物综合研究尽管寒冷缺氧的海洋沉积物似乎是一个不适合生命生存的地方，但它们却充满了具有不寻常代谢能力的微生物。它们在今天和过去的有机物质全球循环中发挥着关键作用，对于我们理解宇宙中其他地方的生命也很重要。虽然以前的研究已经考虑过这样的环境，但仍然存在许多关于那里发生的微生物群落和过程的问题。本项目的目标是进一步了解在寒冷缺氧系统中发生的过程，并将对过程的理解与参与的微生物群落联系起来。更具体地说，该项目将在一个永久寒冷、缺氧的海湾进行生物地球化学实验，结合复杂的化学分析、培养依赖和独立的鉴定技术，以及对从该地点分离的微生物的实验室研究，以提供对这种全球重要环境的微生物学和生物地球化学的更全面的了解。具体目标包括：1.确定研究地点的原核生物群落结构（Skan Bay，AK）。将使用几种独立的技术，包括培养依赖性（最可能数分析，分离）和培养无关性（使用16 SrRNA，DGGE，物种特异性荧光探针，脂质生物标志物分析的完整深度图谱）鉴定技术。确定现场碳和能量流的路径和热力学。将利用几种独立的方法，包括以下天然同位素变化（脂质生物标志物同位素分析- 2 H和13 C，甲烷同位素分析- 2 H和13 C），利用同位素标记的示踪剂（14 C标记的甲烷，乙酸盐，葡萄糖），并确定重要代谢物（CH 4，SO 4 2-和H2）的深度分布。分离和鉴定新的嗜冷和耐冷原核生物，包括产甲烷菌、硫酸盐还原菌、氨基酸降解菌和甲烷氧化菌。将所有的实验室和现场研究与先前的研究相结合，以开发寒冷缺氧环境中微生物-生物地球化学的概念模型。该项目还将深入了解微生物对甲烷水合物的形成和消耗。这项工作也将导致几种新的原核生物的分离和鉴定能够在低温下生长，包括硫酸盐还原菌，产甲烷菌，甲烷氧化菌，和氨基酸消耗syntrophs。此外，这项工作将有助于确定厌氧甲烷氧化的机制和生物负责。这项工作的结果预计将广泛适用于其他极端环境。

LExEn: Integrated Biogeochemical and Microbiological Studies of Cold, Anoxic EnvironmentsAlthough cold, anoxic marine sediments are a seemingly inhospitable location to support life, they are populated by microbes with unusual metabolic capabilities. They play a key role in the global cycling of organic matter today and in the past, and are also important for our understanding of life elsewhere in the Universe. Although previous studies have considered such environments, numerous questions still remain about the microbial communities and processes which occur there. The objectives of the current project are to further the understanding of the processes occurring in cold, anoxic systems, and to link the understanding of the processes with the microbial communities that participate. More specifically, this project will couple biogeochemical experiments performed at a permanently-cold, anoxic bay with sophisticated chemical analyses, culture-dependent and independent identification techniques, and laboratory-based studies of microbes isolated from the site, to provide a more comprehensive understanding of the microbiology and biogeochemistry of such globally-important environments.Specific Goals Include:1. Determine the prokaryotic community structure of the study site (sediments of Skan Bay, AK). Several independent techniques will be utilized encompassing both culture-dependent (most-probable- number analysis, isolations) and culture-independent (complete depth-profile using 16SrRNA, DGGE, species-specific fluorescent probes, lipid biomarker analysis) identification techniques.2. Determine the pathways and thermodynamics of carbon and energy flow at the site. Several independent approaches will be utilized including following natural isotopic variations (lipid biomarker isotope analysis - 2 H and 13 C, methane isotope analysis - 2 H and 13 C), utilizing isotope-labeled tracers (14 C-labeled methane, acetate, glucose), and determining depth profiles of important metabolites (CH4, SO4 2- , and H2).3. Isolate and characterize novel psychrophilic and psychrotolerant prokaryotes, including methanogens, sulfate reducing bacteria, amino-acid degrading syntrophs, and methane oxidizers.4. Integrate all laboratory and field studies with prior studies to develop a conceptual model of the microbial-biogeochemistry of cold, anoxic environments.This project will also yield insight into the formation and consumption of methane hydrates by microbes. This work should also lead to the isolation and characterization of several novel prokaryotes capable of growth at low temperature, including sulfate-reducing bacteria, methanogenic Archaea, methane-oxidizing Archaea, and amino-acid consuming syntrophs. In addition, this work will help to identify the mechanism and organisms responsible for anaerobic methane oxidation. Results of this work are expected to be broadly applicable to other extreme environments.